Continuous tunnel kilns having a rotary roller sole for firing ceramic materials



y 1, 1969 A. BOSSETTI 3,452,408

CONTINUOUS TUNNEL KILNS HAVING A ROTARY ROLLER SOLE FOR FIRING CERAMICMATERIALS Filed Dec. 19, 1966 INVENTOR Ape/4N0 fiosssrr/ BY y-JWATTORNEYS United States Patent .0

Int. Cl. 1 27b 9/00 U.S. Cl. 25-142 2 Claims ABSTRACT OF THE DISCLOSUREA continuous tunnel kiln has a sole comprised of rotating rollers forsupporting ceramic workpieces during firing, the rollers being hollowfor the reception of gas burners and multiperforate for the escape ofcombustion gases.

This invention relates to a continuous tunnel kiln for firing anyceramic materials having each sole of its tunnel (which has to be runthrough by the firing material) constituted by one or more adjacenttunnels provided with a set ,of rollers disposed transversely in respectto the tunnel, said rollers projecting from the kiln wall towards theoutside, to cause, rotating all together, the advancing of the materialcarrying plates. Expedients and arrangements are provided to preventmaterial under firing from hindering the furnace operation should theplate carrying said material break, which can occur fairly easily, dueto the high temperatures reached in these kilns.

The rollers provided for advancing the plate carrying thescharge arehollow, with circular section and have relatively thin walls, tofacilitate their cooling. They are located transversely in adaptedgrooves of the upper layer, they are not adjacent but spaced apart andprotrude slightly relative to the upper sole level of the tunnel. Thedistance between the rollers outside surface and that of the cavity isreduced to the minimum.

In addition, the sole according to this invention is formed of twoseparate superimposed layers, each of them being either continuous orformed by block elements; moreover, each layer is provided withtransverse chambers, it being possible to arrange electrical heatingmeans both within the chambers of the upper layer (that is, within thespace between the rollers) and within the lower chambers, and possiblywithin both of them.

Furthermore, according to the present invention there is provided smallgas burners arranged within said transverse chambers in lieu of theelectrical heating means, the chambers preferably having suitable holesfor exhausting the combustion products.

This invention further provides small gas burners arranged also or onlywithin all or part of the rotary rollers, each roller within which aburner is located preferably having suitable holes for exhausting thecombustion products.

The present invention will be further described, by way of example, withreference to the accompanying drawings in which:

FIG. 1 is an elevational view according to line 11 of FIGURE 2 showing akiln for firing ceramic materials according to the present invention;

FIG. 2 shows a horizontal section taken along the line 2-2 of FIGURE 1,looking in the direction of the arrows; and

FIG. 3 is a detail of FIGURE 1, showing in perspective view thestructure of the cavities of the upper layer, each cavity being adaptedto receive a gas burner.

3,452,408 Patented July 1, 1969 Each kiln tunnel has, as its sole, alayer 6 of refractory material provided with transverse chambers 2,suitable for receiving a gas burner for heating purposes; such a layer 6shall (or may) constitute besides the bottom for the channel considered,also the ceiling for an underlying channel (not shown). The uppersurface 3 of overlying layer 3 is shaped so as to define transversegrooves 4, in which the rollers 5 are mounted and rotate, as Well astransverse chambers 2'. The arrangement for one or more gas burners isprovided within one or more of said chambers 2, which chambers arepractically on the level of the roller axes and between one roller andthe adjacent one.

Chambers 2 and 2' preferably have a plurality of holes 8 for the exhaustof combustion products.

The arrangement of small gas burners interconnected by a plurality ofsupply conduits is provided within all or some of rollers 5; preferably,each roller 5 has a plurality of holes 8 for the exhaust of combustionproducts, or other purposes hereinafter explained.

The gas burners are arranged within rollers 5 in addition to or in lieuof the above-cited burners provided within chambers 2 and 2'.

Rollers 5 may be cooled by air, which emerging from holes 8' also willserve as secondary air combustion for the burners arranged within saidrollers and/or chambers 2 and 2, as well as for causing the atmospherewithin the kiln to become oxidative if such air is supplied in asuitable amount. In rollers 5, wherein the gas burners are arranged,there can also be effected a combustion with an excess of gas so as toprovide a reducing atmosphere in the kiln, through the holes 8'.

The control for the rollers and the other details of construction of thekiln will not be herein described since they are already known by thepersons skilled in the art.

It is apparent also that some modifications or changes shall be made bythose skilled in the art to the above described embodiment, withoutdeparting from the protective limits of the present invention.

What is claimed is:

1. In a furnace for ceramic material, the furnace having a vault and asole, the sole having a continuous bottom and a plurality oftransverselyextending spacers extending across said bottom, said spacers definingtransverse grooves between them, rollers mounted for rotation in andextending lengthwise of said transverse grooves and protruding a shortdistance above said spacers, said spacers having cavities for heatingmeans therein extending lengthwise of said spacers and disposed betweenupper portions of said spacers and said continuous bottom; theimprovement in which said rollers are hollow for the reception of gasburners therein, and said rollers have openings extending therethroughfor the passage of combustion gases from the hollow interior of therollers through said openings and into the furnace.

2. In a furnace for ceramic material, the furnace having a vault and asole, the sole having a continuous bottom and a plurality oftransversely extending spacers extending across said bottom, saidspacers defining transverse grooves between them, rollers mounted forrotation in and extending lengthwise of said transverse grooves andprotruding a short distance above said spacers, said spacers havingcavities for heating means therein extending lengthwise of said spacersand disposed between upper portions of said spacers and said continuousbottom; the improvement in which said cavities contain gas burners andare in communication both with each other and with 3 4 the inside of thekiln through holes, to allow the passage References Cited of the fuelgases towards the inside of the kiln, said UNITED STATES PATENTS rollersbeing hollow for the reception of gas burners 3,110,075 11/1963 Bossatti25 14Z therein, and said rollers having openings extending there-3,135,037 5/1964 Bossatti through for the passage of combustion gasesfrom the 5 3,262,17 7 196 B ni 25 14 hollow interior of the rollersthrough said openings and into the furnace WILLIAM J. STEPHENSON,Primary Exammer.

